1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal driving circuit.
2. Description of the Related Art
As for a driving circuit of a liquid crystal display device according to the related art, for example, a technology disclosed in JP-A-5-46123 (pages 2 to 3 and FIG. 1) has been known. According to the related art technology, in a liquid crystal display device in which an active matrix-type liquid crystal panel is driven to display, a first gate driver that sequentially drives odd-numbered scanning lines of the liquid crystal panel and a second gate driver that sequentially drives even-numbered scanning lines are provided. Accordingly, the odd-numbered scanning lines and the even-numbered scanning lines of the liquid crystal panel are scanned by the first and second gate drivers, respectively, and thus scanning time of each scanning becomes twice as much as the related art. Therefore, even when the number of scanning lines is increased, sufficient writing time of liquid crystal is ensured.
In the above-described related art technology, however, pulses (source pulses) of image signals to be supplied to display elements corresponding to pixels on the liquid crystal panel and pulses (gate pulses) for writing the image signals into the display elements become effective with same timing. Accordingly, when the liquid crystal panel is driven to display at high speed, if the width of the source pulse is decreased, the width of the gate pulse is decreased accordingly, which causes insufficient writing time of liquid crystal. For this reason, even when the number of scanning lines is increased for the sake of the large pixels of the liquid crystal display device, the liquid crystal panel is difficult to be driven to display at high speed. As a result, sufficient display performance cannot be ensured.
In particular, in a case in which TFTs (thin film transistors) on an active matrix substrate of a liquid crystal display device are made of amorphous silicon (a-Si) having low mobility, and the gate drivers are built in the active matrix substrate by use of the TFTs, the above-described problem drastically occurs. Further, at the worst, with the decrease of the width of the gate pulse, the gate driver may be disabled. Amorphous silicon (a-Si) is attracting attention because of a manufacturing process at low costs. Accordingly, it is important to allow the liquid crystal panel to be driven to display at high speed and to implement the large pixels of the liquid crystal display device.